Serum Levels of Thyroid Hormones, Thyroxine-Binding Globulin and Thyrotropin in Arterial and Venous Cord Blood in Newborn Infants Are Identical

Thyroxine, tri-iodothyronine, reverse tri-iodothyronine, free tri-iodothyronine, free thyroxine, tri-iodothyronine resin uptake, thyrotropin, thyroxine-binding globulin and free thyroxine index in both arterial and venous cord blood of 20 normal full-term newborn infants were investigated. There was little difference in the values in arterial and venous cord blood in all examinations. The results suggest that venous cord blood, which is more easily obtainable in sufficient quantity than arterial cord blood, and arterial cord blood are equally useful in the determination of thyroid function in the newborn infant.